Patent Application
20090079783
This invention relates generally to printing and more particularly, to printing mixtures of compressed fluids and marking materials through micro-machined components.
Many marking technologies exist for creating marks or patterns on a substrate. The ink jet printing technology commonly known as “drop-on-demand” provides ink droplets (typically including a dye or a mixture of dyes) for impact upon a recording surface using a pressurization actuator (thermal, piezoelectric, etc.). Selective activation of the actuator causes the formation and ejection of a flying ink droplet that crosses the space between the printhead and the print media and strikes the print media. The formation of printed images is achieved by controlling the individual formation of ink droplets, as is required to create the desired image. Typically, a slight negative pressure within each channel keeps the ink from inadvertently escaping through the nozzle, and also forms a slightly concave meniscus at the nozzle, thus helping to keep the nozzle clean.
Activation of a pressurization actuator produces an ink jet droplet at orifices of a print head. Typically, one of two types of actuators is used including heat actuators and piezoelectric actuators. With heat actuators, a heater, placed at a convenient location, heats the ink causing a quantity of ink to phase change into a gaseous bubble that raises the internal ink pressure sufficiently for an ink droplet to be expelled. With piezoelectric actuators, an electric field is applied to a piezoelectric material possessing properties that create a mechanical stress in the material causing an ink droplet to be expelled. The most commonly produced piezoelectric materials are ceramics, such as lead zirconate titanate, barium titanate, lead titanate, and lead metaniobate.
Conventional ink jet printers are disadvantaged in several ways. For example, in order to achieve very high quality images while maintaining acceptable printing speeds, a large number of discharge devices located on a printhead need to be frequently actuated thereby producing an ink droplet. While the frequency of actuation reduces printhead reliability, it also limits the viscosity range of the ink used in these printers. Typically, adding solvents such as water, etc. lowers the viscosity of the ink. The increased liquid content results in slower ink dry times after the ink has been deposited on the receiver, and this decreases overall productivity. Additionally, increased solvent content can also cause an increase in ink bleeding during drying which reduces image sharpness, negatively affecting image resolution and other image quality metrics. For receivers such as plain paper, excessive liquid can also lead to local mechanical buckling of the receiver.
Conventional ink jet printers are also disadvantaged in that the discharge devices of the printheads can become partially blocked and/or completely blocked with ink. In order to reduce this problem, solvents, such as glycol, glycerol, etc., are added to the ink formulation, which can adversely affect image quality. Alternatively, discharge devices are cleaned at regular intervals in order to reduce this problem. This increases the complexity of the printer.
Other technologies that deposit a dye onto a receiver using gaseous propellants are known. For example, E. Peeters et al., in U.S. Pat. No. 6,116,718, issued Sep. 12, 2000, disclose a print head for use in a marking apparatus in which a propellant gas is passed through a channel, the marking material is introduced controllably into the propellant stream to form a ballistic aerosol for propelling non-colloidal, solid or semi-solid particulate or a liquid, toward a receiver with sufficient kinetic energy to fuse the marking material to the receiver. A disadvantage of this technology is that the marking material and propellant stream are two different entities. When the marking material is added into the propellant stream in the channel, a non-colloidal ballistic aerosol is formed prior to exiting the print head. This non-colloidal ballistic aerosol, which is a combination of the marking material and the propellant, is thermodynamically not stable. As such, the marking material is prone to settling in the propellant stream which, in turn, can cause marking material agglomeration, leading to nozzle obstruction and poor control over marking material deposition.
Technologies that use supercritical fluid solvents to create thin films are also known. For example, R. D. Smith in U.S. Pat. No. 4,734,227, issued Mar. 29, 1988, discloses a method of depositing solid films or creating fine powders through the dissolution of a solid material into a supercritical fluid solution and then rapidly expanding the solution to create particles of the marking material in the form of fine powders or long thin fibers, which may be used to make films. C. Lee et al. in U.S. Pat. No. 4,923,720, issued May 8, 1990, disclose a liquid coating process and apparatus in which supercritical fluids, such as supercritical carbon dioxide, are used to reduce to application consistency viscous coating compositions to allow for their application as liquid sprays. In these disclosures the free-jet expansion of the supercritical fluid solution results in sprays with a shape that cannot be used to create high-resolution patterns on a receiver without a mask.
U.S. Pat. No. 6,752,484 entitled “Apparatus And Method of Delivering A Beam of A Functional Material To A Receiver” by R. Jagannathan et al. discloses a method and apparatus for delivering a solvent free marking material to a receiver wherein the discharge device is shaped to produce a collimated beam of the marking material with the fluid being in a gaseous state at a location beyond the outlet of the discharge device. Thus, this method describes delivering of marking materials in a manner such that it solves many of the drying related problems inherent to conventional, solvent based systems.
U.S. Pat. No. 6,971,739 entitled “Method And Apparatus For Printing” issued Dec. 6, 2005 by S. Sadasivan et al. describes a printhead for delivering marking material to a receiver includes a discharge device having an inlet and an outlet with a portion of the discharge device defining a delivery path. An actuating mechanism is moveably positioned along the delivery path. A material selection device has an inlet and an outlet with the outlet of the material selection device being connected in fluid communication to the inlet of the discharge device. The inlet of the material selection device is adapted to be connected to a pressurized source of a thermodynamically stable mixture of a fluid and a marking material, wherein the fluid is in a gaseous state at a location beyond the outlet of the discharge device.
U.S. Pat. No. 6,672,702 by S. Sadasivan et al. entitled “Method and Apparatus for Printing, Cleaning and Calibrating” describes a printing apparatus comprising: a pressurized source of a thermodynamically stable mixture of a compressed fluid and a marking material; a pressurized source of a compressed fluid; a material selection device having a plurality of inlets and an outlet, one of the plurality of inlets being connected in fluid communication to the pressurized source of compressed fluid and another of the plurality of inlets being connected in fluid communication to the thermodynamically stable mixture of the compressed fluid and the marking material; a printhead, portions of the printhead defining a delivery path having an inlet and an outlet, the inlet of the delivery path being connected in fluid communication to the outlet of the material selection device; and an actuating mechanism moveably positioned along the delivery path, wherein, the compressed fluid is in a gaseous state at a location beyond the outlet of the delivery path; and a cleaning station positioned relative to the printhead, wherein the printhead is moveable to a position over the cleaning station. This patent also includes a marking material measuring device useful for calibrating the amount of marking material being delivered to the substrate.
U.S. Pat. No. 6,595,630 by R. Jagannathan et al. entitled “Method And Apparatus For Controlling Depth of Deposition of a Solvent Free Functional Material In A Receiver” describes a method of delivering a functional material to a receiver comprising in order: providing a mixture of a fluid having a solvent and a functional material; causing the functional material to become free of the solvent; causing the functional material to contact a receiver having a plurality of layers and causing the functional material to penetrate and pass through the first layer of the receiver and penetrate a second layer of the receiver such that the second layer primarily contains the functional material.
For broad use applications, there is still a need to employ discharge devices that enable efficient mass manufacturing of printing systems that use compressed fluids based marking materials. Micro-machined devices are advantageous from that perspective although with shrinking dimensions come many challenges of material properties, ability to design and fabricate micro-machined structures to perform under high pressures, and operating without clogging of micro-nozzles. Micro Electro Mechanical Systems (MEMS) are used in many mass-market commercial devices such as accelerometers, pressure sensors, ink jet printer heads, and digital mirror arrays for projectors.
The ability to develop viable MEMS in any new area is to a large degree enabled and constrained by the set of materials and micro-machining processes from which a designer can select. Hitherto the vast majority of commercial MEMS have utilized the Complementary Metal Oxide Semiconductor (CMOS) and Very Large Scale Integration (VLSI) materials and process set. Details of such materials and processes are available in published literature including, for example, Introduction to Micro Fabrication by Sami Franssila, 2004, John Wiley and Sons, Ltd. So far, viable MEMS for printing with compressed fluids have not been disclosed. For such a system, in addition to known problems of nozzle shape, control valves, and their effect on jet collimation, a number of other problems need to be solved. For example, it is not obvious whether CMOS/VLSI materials can withstand the high pressures required for use in a compressed fluid printing process and that they can be useful for making micro-machined nozzles. Also, it is not obvious which materials and methods may provide a leak-proof connection from the high-pressure source of the marking material to the micro-machined nozzles. Methods that work at macro-scale do not necessarily work at micro-scale because uniformity of material properties and distribution of mechanical forces during assembly become more exacting.
Another problem with printing using compressed fluid formulations is that some portion of the jetted marking material that is in the form of nanometer size particles, not Pico-liter sized droplets, may escape along with the effluent gas into the nearby environment and create a potential health hazard. The printing system should be designed to minimize or eliminate such exposure to operators. The collection of such materials is fundamentally different from other continuous ink jet systems where the Pico-liter sized droplets are collected in a gutter when they are not intended to go to the substrate for printing.
Furthermore, many marking materials have a limited solubility in the pure compressed fluids and that limits the scope of this technology. Using conventional solvents as co-solvents with compressed fluids can enhance the solubility. While spray coating technologies for conventional solvent containing compressed fluids are known, directed beam printing with such fluids is not reported.
In accordance with one embodiment of the present invention, a printing apparatus is disclosed for delivering a mixture of compressed fluid and marking material and depositing the marking material in a pattern onto a substrate. The apparatus includes a high pressure source of a mixture of compressed fluid and marking material. A micro-machined manifold includes a plurality of micro-nozzles, a fluid chamber, an entrance port, and a first surface and a second surface. Portions of the first surface define the entrance port, the entrance port being connected in fluid communication with the fluid chamber. Each of the micro-nozzles have an inlet and an outlet, the inlet being connected in fluid communication with the fluid chamber, the outlet being located on the second surface. Each micro-nozzle is shaped to produce a directed beam of the mixture of compressed fluid and marking material beyond the outlet of the micro-nozzle. A housing is connected in fluid communication with the high pressure source and the entrance port of the micro-machined manifold, the connection between the housing and the micro-machined manifold being a sealed connection.
In accordance with another embodiment of the present invention the printing apparatus further comprises a device operable to capture marking material that does not adhere to the substrate.
In accordance with yet another embodiment of the present invention, a method of printing is disclosed. The method comprises providing a high pressure source of a mixture of compressed fluid and marking material; providing a micro-machined manifold including a first surface and a second surface, portions of the first surface defining an entrance port, the entrance port being connected in fluid communication with a fluid chamber, a plurality of micro-nozzles each having an inlet and an outlet, the inlet being connected in fluid communication with the fluid chamber, the outlet being located on the second surface, each micro-nozzle being shaped to produce a directed beam of the mixture of compressed fluid and marking material beyond the outlet of the micro-nozzle; providing a housing connected in fluid communication with the high pressure source and the entrance port of the micro-machined manifold; and controlling the pressure of the mixture of compressed fluid and marking material to create a directed beam of the mixture of compressed fluid and marking material beyond each outlet of each micro-nozzle.
An advantage of the present invention is that CMOS/VLSI materials and processes can be used to make micro-machined manifolds for printing with compressed fluids. This enables low-cost mass production of micro-machined manifolds. Another advantage is the simple sealing methods like clamped gaskets can be used to provide leak-proof connection between the micro-machined manifold and the high-pressure source. Another advantage of the present invention is that marking material and effluent gases that escape during printing can be collected to provide a safer operation. A further advantage is that a wide variety of materials including those using conventional solvents as co-solvents can be directly printed with the apparatus disclosed in this invention.
In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which:
The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. Additionally, materials identified as suitable for various facets of the invention, for example, marking materials, solvents, equipment, etc. are to be treated as exemplary, and are not intended to limit the scope of the invention in any manner.
The high-pressure source 20 can be made out of any suitable materials that can safely operate at the formulation conditions. Desirable high pressure source materials should withstand an operating pressure range from 0.001 atmospheres (1.013×102 Pa) to 1000 atmospheres (1.013×108 Pa) in pressure and a temperature range from −25 degrees Centigrade to 1000 degrees Centigrade. Typically, the preferred materials include various grades of high-pressure stainless steel. However, it is possible to use other materials if the specific deposition or etching application dictates less extreme conditions of temperature and/or pressure. The high-pressure source 20 should also be precisely controlled with respect to the operating conditions (pressure, temperature, and volume). The solubility/dispersibility of marking materials depends upon the conditions within the high-pressure source 20. As such, small changes in the operating conditions within the high-pressure source 20 can have undesired effects on marking material solubility/dispensability.
Materials that are above their critical point, defined by a critical temperature and a critical pressure, are known as supercritical fluids. The critical temperature and critical pressure typically define a thermodynamic state in which a fluid or a material becomes supercritical and exhibits gas like and liquid like properties. Materials that are at sufficiently high temperatures and pressures below their critical point are known as compressed liquids. The fluid contained in the high-pressure source 20 may include a compressed liquid having a density equal to greater than 0.1 g per cubic centimeter; or a supercritical fluid having density equal to or greater than 0.1 g per cubic centimeter; or a compressed gas having a density equal to or greater than 0.1 g per cubic centimeter or any combination thereof. The fluid contained in the high-pressure source 20 may also include any solvent or mixture of solvents that are miscible with the supercritical fluids and/or compressed liquids. Ambient conditions are preferably defined as temperature in the range from −100 to +100° C., and pressure in the range from 1×10−3-100 atmosphere for this application. Materials in their supercritical fluid and/or compressed liquid state that exist as gases at ambient conditions find application here because of their unique ability to solubilize and/or disperse functional materials of interest in the compressed liquid or supercritical state. In the context of this invention, the compressed fluid mixture contained in the high-pressure source 20 includes any fluid that dissolves/solubilizes/disperses a marking material where at least one fluid is gas at ambient pressure and temperature. In many cases, the compressed fluid mixture may also include conventional organic solvents as co-solvents. The combination of marking material and compressed fluid is typically referred to as a mixture, formulation, composition etc. The mixture or formulation of marking material and compressed fluid is called thermodynamically stable when the marking material is dissolved or dispersed within the compressed fluid in such a fashion as to be indefinitely contained in the same state as long as the temperature and pressure within the high-pressure source are maintained constant. This state is distinguished from other physical mixtures in that there is no settling, precipitation, and/or agglomeration of marking material particles within the high-pressure source unless the thermodynamic conditions of temperature and pressure within it are changed.
Compressed fluids include but are not limited to: carbon dioxide, nitrous oxide, ammonia, xenon, ethane, ethylene, propane, propylene, butane, isobutane, chlorotrifluoromethane, monofluoromethane, sulfur hexafluoride and mixtures thereof. Carbon dioxide is generally preferred as the compressed fluid of choice in many applications due to its low cost, wide availability, and usable temperature and pressure ranges.
Suitable conventional solvents include but are not limited to: ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone and other aliphatic ketones; esters such as methyl acetate, ethyl acetate, alkyl carboxylic esters, methyl t-butyl ethers, di-butyl ether, methyl phenyl ether, other aliphatic or alkyl aromatic ethers; glycol ethers such ethoxyethanol, butoxyethanol, ethoxypropanol, propoxyethanol, butoxypropanol, and other glycol ethers; glycol ether esters such as butoxyethoxy acetate, ethyl ethoxy propionate and other glycol ether esters; alcohols such as methanol, ethanol, propanol 2-propanol, butanol, amyl alcohol and other aliphatic alcohols; aromatic hydrocarbons such as toluene, xylene, and other aromatics or mixtures of aromatic solvents; and nitro alkanes such as 2-nitropropane. Generally the solvents suitable for this invention must have the aforementioned miscibility and must also be able to wet or be a good solvent for the marking material. Typically the ratio of solvent to marking material is from about 0.01:1 to about 100:1 where as typically the ratio of compressed fluid to marking material is from about 1×105:1 to about 4:1.
The marking material may be a solid or a liquid, but it is preferred that it is solid. Additionally, the marking material can be an organic molecule, a polymer molecule, a metallo-organic molecule, an inorganic molecule, an organic nanoparticle, a polymer nanoparticle, a metallo-organic nanoparticle, an inorganic nanoparticle, an organic microparticles, a polymer micro-particle, a metallo-organic microparticle, an inorganic microparticle, and/or composites of these materials, etc. Suitable polymers include vinyl, acrylic, styrenic and interpolymers of the base vinyl, acrylic and styrenic monomers; polyesters, alkyds, polyurethanes, cellulosic esters, amino resins, natural gums and resins, and cross-linkable film forming agents. Additionally, any suitable surfactant and/or dispersant material that is capable of solubilizing/dispersing the marking materials in the compressed fluid mixture for a specific application can be incorporated into the combination of marking material and compressed fluid mixture. Such materials include, but are not limited to, cyclodextrins, fluorinated polymers such as perfluoropolyether, siloxane compounds, etc. However, such polymeric materials often cause printing nozzle clogging. Therefore, it is also advantageous to use marking materials that have higher solubility in CO2. Such materials obviate the need for polymeric surfactants for solubilization. A general design principle for CO2-compatible materials is to tether the desired substances to one or more solubilizers with a very high affinity for CO2 (See paper by E. Beckmann entitled “A Challenge for Green Chemistry: Designing Molecules that Readily Dissolve in Carbon Dioxide” published in Chem. Commun. 2004, Vol. 17, pp. 1885). P. Raveendran and S. Wallen disclose in U.S. Patent Application No. 20030072716 entitled “Renewable, carbohydrate based CO2-philes” a composition comprising a carbohydrate-based material dispersed in carbon dioxide. The carbohydrate-based material comprises a carbohydrate and at least one non-fluorous CO2-philic group. Carbon dioxide can be supercritical, liquid or gaseous. The carbohydrate can be a monosaccharide, a disaccharide, a trisaccharide, a polysaccharide, a cyclic saccharide or an acyclic saccharide. The CO2-philic group is selected from the group consisting of an acetyl group, a phosphonyl group, a sulfonyl group, —O—C(O)—Rn, —C(O)—Rn, —O—P(O)—(O—Rn)2, and —NRnRn′ where Rn and Rn′ are independently hydrogen or an alkyl group. They also disclose a method of forming a composition comprising a carbohydrate-based material dispersed in carbon dioxide. In a preferred embodiment, the method comprises: (a) providing a CO2-phobic carbohydrate comprising one of one or more hydroxyl groups and one or more or ring hydrogens; (b) chemically replacing at least one of a hydroxyl group and a ring hydrogen with a non-fluorous CO2-philic group to form a carbohydrate-based material; and (c) dispersing the carbohydrate-based material in carbon dioxide, whereby a composition comprising a carbohydrate-based material dispersed in carbon dioxide is formed. Similarly, an example of CO2-phobic dyestuff tethered to CO2-phillic vinyl acetate oligomer was reported in a paper by B. Tan and A. Cooper entitled “Functional Oligo (Vinyl Acetate) CO2-philes for Solubilization and Emulsification” in J. Am. Chem. Soc., 2005, Vol. 127, pp. 8938). In general, the ‘CO2-phobic’ part can be a functional unit such as a dyestuff, a polymer, a reagent or a catalyst, or it might be designed to interact with other CO2-insoluble molecules, giving the whole ensemble the function of a surfactant. All such variations in marking material are contemplated for use with the present invention.
During operation of printing apparatus 10 a substrate 60, which may be supported by a substrate conveyance mechanism 62, is spaced relative to the outlets of the micro nozzles 40. The substrate conveyance mechanism 62 can be utilized to maintain the substrate 60 at a defined distance from the outlets of the micro nozzles 40 and for interfacing with external positioning equipment as required by the particular application.
When operating printing apparatus 10, the high-pressure source 20 of the mixture of compressed fluid and marking material are maintained at a desirable temperature and pressure. The conduit 52 and housing 50 are also maintained at a desired temperature usually within ±50° C. of the temperature inside the high-pressure source. When on/off valve 22 is opened the mixture of compressed fluid and marking material is delivered in to the fluid chamber 38 of the micro-machined manifold 30 and exits through the outlets 44 of the micro-nozzles 40 as directed beams 64 of the mixture of compressed fluid and marking material. A directed beam keeps the marking material along a narrow path in space. The divergence angle of the directed beam is the angle made by the boundary of the directed beam with the line perpendicular to the second surface 34 at the outer edge of the micro-nozzle. A pattern is a set of markings having defined spatial characteristics (for example, lines, letters, shapes etc.). The directed beams 64 are projected on to the substrate 60 thereby depositing the marking material in a pattern on the substrate 60. The divergence angle can be calculated from knowing the distance from the second surface 34 at the micro-nozzle outlet 44 to the facing surface of the substrate 61 and by measuring the dimensions of the printed features on the substrate 60. It is preferred that the divergence angle of the directed beam is less than 10 degrees, more preferably less than 5 degrees, and most preferably less than 3 degrees.
The printing apparatus 10, shown in
Details of micro machining processes can be found in any standard textbook on Micro fabrication such as Introduction to Micro Fabrication by Sami Franssila, 2004, John Wiley and Sons, Ltd. The micro-machined manifold 30 can be made prepared from single crystalline, polycrsystalline or amorphous silicon wafers or from other materials including quartz (SiO2), gallium arsenide (GaAs), silicon carbide (SiC), fused silica, sapphire, alumina, other glasses, polymers or stainless steel. Usually the micro-machined manifold 30 would be manufactured in the following sequence. Typically the fluid chambers 38 would be prepared first by a deep reactive ion etch (DRIE) process. The through holes would then be etched. After micro machining the two parts are cleaned, aligned and then bonded together at the bond surfaces 35. Bonding may be performed by any direct or indirect bonding technique with deposited layers. Suitable bonding techniques include fusion bonding, anodic bonding, thermo-compression bonding or adhesive bonding. After bonding the wafers together they are diced to final dimensions.
The micro-nozzles 40 can have a constant cross sectional area or a variable cross sectional area along their length. Various nozzle designs have been disclosed in U.S. Pat. No. 6,752,484 and are incorporated herein by reference. Typical dimensions for features in any of the micro-machined manifold designs 30, 30′ or 30″ are in the range of 0.1 μm to 2000 μm. The length of the micro-nozzles 40 can be 0.10 to 2000 μm long, depth can be in the range of 0.1 to 500 μm, and width can be in the range of 0.1 to 500 μm. More preferably the length of the micro-nozzles 40 can be 50 to 1000 μm long, depth can be in the range of 5 to 100 μm, and width can be in the range of 5 to 100 μm. Most preferably the length of the micro-nozzles 40 can be 50 to 900 μm long, depth can be in the range of 5 to 50 μm, and width can be in the range of 5 to 50 μm. The fluid chamber 38 can be designed to dampen out any flow disturbances while distributing the flow. However, it may be advantageous to minimize its volume in some instances. Similarly it may also be advantageous to minimize the through holes' 37 volumes.
When printing with compressed fluids such as CO2 the gas undergoes rapid expansion and the marking material is carried along originally at the velocity of the gas. Typically, the marking material exists in the directed beam as nano-scale particles that are less than 1 μm in diameter, and many of them can be nano-particles with diameter less than 0.1 μm. When these nano-scale particles approach a substrate, they may adhere to the surface, get embedded below the surface or bounce off the surface of the substrate. It is advantageous to collect any particles of marking material that bounce off the surface of the substrate. A particle collection means incorporating a suction means has been developed for this purpose.
The substrate can be positioned on a substrate conveyance mechanism 62 that is used to control the movement of the substrate during the operation of the printing apparatus 100. The substrate conveyance mechanism 62 can be a drum, an x, y, z translator, any other known media conveyance mechanism, etc. The printhead position can also be controlled by an x, y, z conveyance mechanism interfaced to the printhead mounting means 118. The printing apparatus 100 may have the manifold 30 being rigidly connected to the pressurized source such that the micro-machined manifold 30 is stationary and the substrate conveyance mechanism 62 is moveably positioned relative to the micro-machined manifold 30 while maintaining a predetermined distance from the outlets of the micro-nozzles 44 to the substrate. The printing apparatus 100 can also have the substrate conveyance mechanism being moveable in a first direction and the micro-machined manifold 30 being movable in a second direction while maintaining a predetermined distance from the outlets of the micro-nozzles 44 to the substrate. The printing apparatus 100 could also have the micro-machined manifold 30 being flexibly connected to the high-pressure source 20, the manifold being moveable in at least a first direction while the substrate conveyance mechanism 62 is stationary and is used only to retain the substrate 60. In all of these cases the printing apparatus 100 has a conveyance mechanism to control the lateral (x, y) position of the directed beams 64 with respect to the substrate while the substrate 60 is being maintained at a predetermined distance (z) from the outlets of the micro-nozzles 44.
Any of the printing apparatuses 10 disclosed here in could incorporate a cleaning station positioned relative to the printhead, wherein the printhead is moveable to a position over the cleaning station as disclosed in U.S. Pat. No. 6,672,702 by S. Sadasivan et al. The cleaning station may also include a collection means to collect material being cleaned from the printhead 100. Any of the printing apparatuses 10 disclosed here in could also incorporate a calibration station similar to that disclosed in U.S. Pat. No. 6,672,702 by S. Sadasivan et al.
A 250 ml high-pressure vessel was used as the source of the marking material. The vessel had a floating piston, resistive heaters and a mechanical stirrer to allow operation at desired pressure and temperature. The vessel was connected to the housing with stainless steel tubing that was kept at constant temperature with a circulating water jacket. The silicon side of a 9.9 mm long, 2.5 mm wide, and 1.135 mm thick micro-machined glass-silicon manifold was interfaced with the housing by interposing an In (80%)-Pb (15%)-Ag (5%) gasket that had laser cut holes to mate with conduits in the housing.
A homogeneous compressed fluid solution of 240 mg of Dye-1 (a peracetylated glycoconjugated colorant) and 200 g CO2 was prepared in the high-pressure vessel at 40 degrees Centigrade and 100 bar which served as the high-pressure source 20 of compressed fluid and marking material. The molecular structure of Dye-1 was as follows:
A Kodak Photo Quality Ink Jet Paper was used as the substrate 60. The design of Kodak Photo Quality IJ Paper is described in U.S. Pat. No. 6,040,060, which is incorporated herein by reference. Kodak Photo Quality Ink Jet Paper comprises raw paper base that is then resin coated on both sides. Subsequently this paper is coated on one side with two ink-receiving layers. The base layer comprises gelatin and a material selected from the group consisting of carboxymethyl cellulose, polyvinylpyrrolidone, polyvinylalcohol, hydroxyethyl cellulose and mixtures thereof. The top layer comprises a material selected from the group consisting of an acrylic acid-diallyldimethylammonium chloride-hydroxypropyl acrylic copolymer and acrylic acid-diallyldimethylammonium chloride polymer. The top layer is approximately 1-3 μm thick while the base layer that contacts the resin-coated paper is approximately 10-15 micrometers thick.
When the on/off valve 22 between the high-pressure chamber 20 and housing 50 was opened, the compressed fluid mixture flowed through the housing 50 and the micro-machined manifold 30″ before exiting as a directed beam 64 that was directed onto the substrate 60. The substrate was spaced 2 mm away from the micro-nozzle outlets 44 and second surface 34 and was moved laterally at a speed of ca. 2.3 m/min. The resultant line was about 250 μm wide as shown in the photograph shown in
The housing 50 in Example 1 was attached to a different positional control unit that allowed the substrate to move along the x-axis and the housing was now movable—along the y-axis displacing orthogonally back and forth for each new line. Example 1 was then repeated with the following exceptions: (1) Compressed fluid mixture was kept at 125 bar; (2) the substrate 60 was spaced 0.76 mm away from the micro-nozzle outlets 44 at the second surface 43; and (3) the housing 50 and substrate 60 were moved laterally back and forth at a nominal speed of ca. 5.31 m/min. The average line width was ca. 184 μm. (See
Example 2 was repeated with the following exceptions: (1) Compressed fluid mixture was kept at 200 bar; and (2) the housing 50 and substrate 60 was moved laterally back and forth at a nominal speed of ca. 15.93 m/min. The average line width was ca. 104 μm which is equivalent to a divergence angle of 0.15 degrees.
The micro-machined manifold 30″ of Example 2 was replaced with a new micro-machined manifold 30″ made from two silicon wafers that were fusion bonded together. The entrance port of the manifold had a 200 μm diameter circular cross section. It opened into a fluid chamber that was ca. 350 μm wide, 350 μm long and 50 μm deep. This was connected to a micro-nozzle that was rectangular in cross section, 10 μm wide, 50 μm deep and 225 μm long. An experiment was conducted similar to Example 2 with the following operating conditions: (1) Compressed fluid mixture was kept at 100 bar and 40 C; (2) The substrate was placed 0.76 mm away from the micro-nozzle exit; and (2) the housing was moved laterally back and forth at a nominal speed of ca. 5.31 m/min. The average line width was ca. 60 μm (See
A procedure similar to Example 2 was followed but a few changes were made in equipment, materials, and operating conditions as noted below. (1) The micro-machined manifold of Example 2 was replaced with a new manifold made from two silicon wafers that were fusion bonded together. The entrance port of the manifold had a 200 μm diameter circular cross section. It opened into a fluid chamber that was ca. 350 μm wide, 350 μm long and 50 μm deep. At the junction of this chamber to a micro-nozzle, a small structure required flow to pass around it before entering the micro-nozzle. The latter was rectangular in cross section, 20 μm wide, 50 μm deep and 900 μm long. (2) A homogeneous compressed fluid solution of 404 mg of Dye-2 (a peracetylated glycoconjugated colorant), 0.64 g of acetone, and 200 g CO2 was prepared in the high-pressure vessel at 40 C and 100 bar. The molecular structure of Dye-2 was as follows:
(3) The plain paper was used as the substrate and it was placed 1.168 mm away from the micro-nozzle exit; and (4) the housing was moved laterally back and forth at a nominal speed of ca. 26.56 m/min. The average line width was ca. 128 μm which is equivalent to a divergence angle of 1.92 degrees.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.
